Diaphragm operated priming device for centrifugal impeller pump

ABSTRACT

A shaft driven centrifugal impeller pump has a priming arrangement associated with its collector section and drive shaft. A continuously operated diaphragm-type positive displacement pump is operatively connected to a cam mounted on the drive shaft to cause air to flow out of the collector section, into a chamber of the positive displacement pump, out of the chamber and through a conduit connected to the impeller pump&#39;&#39;s discharge line. A spring loaded shutoff valve prevents a flow from the collector section to the discharge line until the fluid pressure in the collector section forces the valve open. A passage interconnects the chamber of the displacement pump and the collector section to pressure balance the diaphragm.

United States Patent [72] Inventor John E. Cygnor Middletown, Conn. [2]] Appl. No. 844,591

[22] Filed July 24, 1969 [45] Patented May 18, 1971 [73] Assignee Chandler Evans Inc.

West Hartford, Conn.

[54] DIAPHRAGM OPERATED PRIMING DEVICE FOR CENTRIFUGAL [MPELLER PUMP 5 Claims, 1 Fig. [52] US. Cl 417/203, 417/199A [51] Int. Cl F04d 9/00 [50] Fieldofsealch 417/201, 199A,202,203; 103/1 13 (A), 113 (A-l) [56] References Cited UNITED STATES PATENTS 2,292,896 8/1942 Morgan 103/1 13 2,472,802 6/1949 Bentley 103/ 1 13 2,666,393 1/1954 Troeger et a1. 103/113 www- 44 46 J6 J6 3a Primary Examiner-Henry F. Raduazo Atmrney-Radford W. Luther ABSTRACT: A shaft driven centrifugal impeller pump has a priming arrangement associated with its collector section and drive shaft. A continuously operated diaphragm-type positive displacement pump is operatively connected to a cam mounted on the drive shaft to cause air to flow out of the collector section, into a chamber of the positive displacement pump, out of the chamber and through a conduit connected to the impeller pumps discharge line. A spring loaded shutoff valve prevents a flow from the collector section to the discharge line until the fluid pressure in the collector section forces the valve open. A passage interconnects the chamber of the displacement pump and the collector section to pressure balance the diaphragm.

PATENTEunmalsm 3578.880

Fifi 7/ 5 5y PM aw fiTTOR/VEV DIAPHRAGM OPERATED PRIMING DEVICE FOR CENTRIFUGAIL IMPELLER PUMP BACKGROUND OF THE INVENTION The invention relates to pump priming devices, and more particularly to pump priming devices associated with centrifugal impeller pumps. Even more particularly, this invention relates to pump priming devices which utilize a positive displacement pump, and still more particularly to priming devices which employ a diaphragm-type positive displacement pump. This invention further relates to automatic pump priming devices.

Positive displacement pumps of the vane and gear type are not readily adaptable to elevate a fluid to a substantial height, such as feet, under dry lift conditions. Also, at these heights such pumps yield marginal performance due to cavitation effects. It is conceivable that a bellows or diaphragm type of pump could be designed to satisfy the required dry lift performance criterion, but it is doubtful that the problems engendered by cavitation effects and sustained running would be susceptible to facile solutions.

The most attractive solution of the above-enumerated difficulties is the utilization of a centrifugal impeller pump because of its relatively low cost and performance characteristics. Two prominent drawbacks to this approach, however, are this type of pumps lack of inherent dry lift capability and tendency to lose prime.

Because of these difficulties, a great many centrifugal pump arrangements embody a priming device which is either manually or automatically operated. It is highly desirable that these priming devices be capable of fully automatic operation in order to avail the operator of the pump of a simple and convenient control procedure, and provide means to reprime the pump in the event that prime is dissipated during operation thereof.

British Pat. No. 918,798 discloses a priming device which automatically primes a centrifugal pump during starting, and reprimes the pump during operation thereof if a loss of prime is encountered therein. This device achieves these results by the inclusion of a mechanism which starts and stops a reciprocating priming pump in accordance with the position of a flow sensing linkage operatively associated with the discharge line of the centrifugal pump; the linkage controlling the position of a spring loaded clutch. Although fully automatic operation is accomplished by this device, it requires a complex clutching arrangement to start and stop the priming pump.

It would then be advantageous to provide a priming device including a priming pump in which the priming pump is continuously running during operation of the centrifugal pump, since the provision of a clutching structure would not be compelled. The reason for disengaging diaphragm operated priming pumps in such arrangements is to forestall the development of injurious pressure loads on the diaphragm of the priming pump that could result in deterioration or failure of the diaphragm.

SUMMARY OF THE INVENTION The instant invention is a centrifugal impeller pump priming device which features a continuously operated, reciprocating diaphragm-type positive displacement priming pump and a novel flow circuit which effects automatic priming during all phases of the impeller pumps operation while occasioning a pressure balance across the diaphragm of the priming pump.

Briefly stated, an inlet conduit interconnects the collector section of an impeller pump and a chamber in which a movable member is mounted. An outlet conduit interconnects the chamber and the impeller pumps discharge line, downstream of a discharge shutoff valve positioned in the discharge line. A passageway communicates fluid pressure from the collector section to the side of the movable member which is not in communication with the inlet and outlet conduits to pressure balance the movable member and thereby alleviate the pres sure differential across the member which otherwise might induce stresses in the member that could eventually lead to failure. The movable member is continuously in motion so that pump prime may be recaptured if it should be dissipated by some operational occurrence. Also continuous operation of the priming pump permits the exclusion of a mechanism to engage and disengage the primingpump in accordance with the pump prime.

It is a primary object of the invention to provide a priming device, including a diaphragm, with means to achieve a pressure balance across the diaphragm.

It is a further object to provide a priming device, in association with a continuously running priming pump, including a diaphragm with a means to restore prime to a centrifugal impeller pump while eliminating the need for a priming pump clutching device.

It is a still further object to provide an impeller pump priming system with a load balanced positive displacement-type priming pump.

Other objects, advantages and novel features will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING The drawing shows a schematic diagram of a priming system according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The drawing schematically illustrates an application of the invention to a centrifugal impeller pump generally indicated at 4. Impeller pump 4 has an inlet 6 to receive an inlet flow of fluid, a rotatable impeller 8, and collector section 9. Impeller pump 4 is drivingly connected to a rotatably mounted shaft 10 which in turn is coupled to a drive element 12 which is adapted to be driven by an engine or other suitable drive means.

A discharge line, formed by connecting segments 14 and 15 and the collector section 9 defines a discharge cavity which has a spring loaded discharge shutoff valve positioned therein for blocking a flow of fluid from the collector section 9 and segment 15 to segment 14 until a sufficient pressure is exerted on face 20 of valve 18 so as to move valve 18 against spring 22 and thereby unseat the valve. As is evident from the drawing, the face 20 of valve 18, the segment 14 and the collector section 9 cooperate to define a cavity 24 in which fluid pressure may build up until the valve 18 is forced open.

A positive displacement pump generally indicated at 28 is comprised of a movable diaphragm member 30 which is sealingly mounted within a chamber so as to divide the chamber into two isolated smaller chambers 32' and 34. Chamber 34 has a fluid inlet port 36 and a fluid outlet port 38 for respectively receiving fluid from he cavity 24 and expelling fluid therefrom to the discharge line segment 14. Inlet conduit 40 and outlet conduit 42 respectively fluidly interconnect chamber 34 with cavity 24 and discharge line segments 14 (downstream of shutoff valve 18). The inlet and outlet connections 40 and 42 are associated with check valves respectively designated at 44 and 46, which are preferably of the reed type, to prevent a return flow in the conduits.

Chamber 32' is fluidly connected to cavity 24 by means of an interconnecting passageway 48, for the purpose of which is to pressure balance the diaphragm by communicating pressure from the cavity to the side of the diaphragm which forms chamber 32. If the diaphragm was not substantially balanced in such a system as illustrated, the unbalanced pressure forces acting upon the diaphragm would be very likely to rupture or otherwise impair the structural integrity thereof, assuming steady-state operating conditions.

Shaft 10 has a cam 52 integrally mounted thereon which is interconnected to a diaphragm 30 by axially movable push rod elements 54 which is urged into tracking engagement with cam 52 by a spring positioned in chamber 34. Element 54 includes a cam follower at its extremity to engage the cam. Rotation of shaft 52 will then move element 54 in an up and down manner so as to impart a similar reciprocating movement to diaphragm 30. The drive mechanism for the positive displacement pump is then constituted by the shaft 10, cam 52. and element 54.

in operation, when drive element rotation, is rotated, a corresponding rotation of shaft is effected, causing the impeller 8 of impeller pump 4 to commence rotation, as well as producing a reciprocating movement of diaphragm 30. Assuming that the fluid to be pumped is fuel and that air presently occupies the voids in the system, it is evident that air will be sucked from cavity 24 to chamber 34 via inlet conduit 40 and expelled therefrom to discharge line segment 14 via outlet conduit 42 during respective downward and upward movements of the diaphragm. The low pressure created in cavity 24 by the reciprocating motion of the diaphragm will tend to suck fuel into the pump 4 from inlet 6, the fuel eventually filling the cavity. As cavity 24 becomes substantially filled with fuel, fuel will begin to flow through conduits 41 and 42. The fuel pressure in cavity 24 will then increase owing to the inability of the priming pump to handle an increased flow through inlet conduit 40. The pressure in cavity 24 will eventually reach a value sufficient to open shutoff valve 18 and thus produce a flow in discharge line segment 14. it should be noted that the fuel flow emerging from the discharge line will be the sum of that passing the shutoff valve and that emerging from outlet conduit 42 as there will always be a small fuel flow through the outlet conduit when the pump is fully primed. The fuel pressure across the diaphragm is substantially balanced by virtue of the communication of pressure in cavity 24 to chamber 32' thereby minimizing the stress thereon.

it is within the scope of the invention to utilize a form of positive displacement pump different from that illustrated, such as a piston-type pump. It would also be possible to apply the teachings of the invention to an alternate type of impeller pump, as for example an axial flow pump.

Obviously many modifications and variations of the present invention are possible in light of the above teachings. It is therefore, to be understood that the invention may be practiced otherwise than as specifically described.

lclaim:

1. In a pump, the combination comprising:

an impeller pump having an inlet and a discharge cavity;

a positive displacement pump having a chamber, a flow inlet port and a flow outlet port, the inlet port and outlet port communicating with the chamber, the positive displacement pump serving to prime the impeller pump;

an inlet conduit means interconnecting the cavity and the inlet port',

an outlet conduit means interconnecting the cavity and the outlet port;

a pair of check valves respectively controlling the inlet and outlet conduit means for preventing return flows therein;

a movable member mounted within the chamber of the positive displacement pump dividing the chamber into two smaller chambers, one of the smaller chambers communicating with the inlet and outlet ports;

a passageway means interconnecting the discharge cavity and the other of said smaller chambers to pressure balance the movable member; and

a drive mechanism operatively connected to the movable member for imparting reciprocating movement thereto.

2. The combination of claim 1, wherein there is further provided:

a discharge shutoff valve mounted in the cavity intermediate the inlet and outlet conduits for blocking a flow from the impeller pump until a sufiicient discharge pressure is exerted thereupon.

3. The combination of claim 1, wherein the drive mechanism comprises:

a rotatable shaft drivingl connected to the impeller pump; a cam integral with the s aft;

an element interconnecting the cam and the movable member such that rotation of the shaft produces reciprocating movement of the movable member. 4. The combination of claim 1, wherein the movable member comprises:

a diaphragm seaiingly mounted to the walls of the chamber of the positive displacement pump. 5. The combination of claim 1 wherein the drive mechanism comprises:

means to continuously impart reciprocating movement to the movable member during operation of the impeller pump. 

1. In a pump, the combination comprising: an impeller pump having an inlet and a discharge cavity; a positive displacement pump having a chamber, a flow inlet port and a flow outlet port, the inlet port and outlet port communicating with the chamber, the positive displacement pump serving to prime the impeller pump; an inlet conduit means interconnecting the cavity and the inlet port; an outlet conduit means interconnecting the cAvity and the outlet port; a pair of check valves respectively controlling the inlet and outlet conduit means for preventing return flows therein; a movable member mounted within the chamber of the positive displacement pump dividing the chamber into two smaller chambers, one of the smaller chambers communicating with the inlet and outlet ports; a passageway means interconnecting the discharge cavity and the other of said smaller chambers to pressure balance the movable member; and a drive mechanism operatively connected to the movable member for imparting reciprocating movement thereto.
 2. The combination of claim 1, wherein there is further provided: a discharge shutoff valve mounted in the cavity intermediate the inlet and outlet conduits for blocking a flow from the impeller pump until a sufficient discharge pressure is exerted thereupon.
 3. The combination of claim 1, wherein the drive mechanism comprises: a rotatable shaft drivingly connected to the impeller pump; a cam integral with the shaft; an element interconnecting the cam and the movable member such that rotation of the shaft produces reciprocating movement of the movable member.
 4. The combination of claim 1, wherein the movable member comprises: a diaphragm sealingly mounted to the walls of the chamber of the positive displacement pump.
 5. The combination of claim 1 wherein the drive mechanism comprises: means to continuously impart reciprocating movement to the movable member during operation of the impeller pump. 